Area Forecast Discussion
Issued by NWS Cleveland, OH

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000
FXUS61 KCLE 192319
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
719 PM EDT Sat May 19 2018

.SYNOPSIS...
Low pressure will move northeast from the Central Great Lakes into
Quebec tonight, with a cold front settling south behind it. Another
area of low pressure will track out of the Plains and move east
along the stalled frontal boundary on Monday. High pressure will
move into the Great Lakes region on Wednesday.

&&

.NEAR TERM /THROUGH SUNDAY NIGHT/...
Made some minor changes to POP`s and hourly temperatures to
reflect current trends.

Previous Discussion...
Showers and scattered thunderstorms will continue into this evening
as an upper level wave lifts northeast across the area. Thunderstorm
strength has been limited by modest instability of 500-1000 J/kg of
ML CAPE coupled with generally weak lapse rates. Convection has been
rather shallow thus far and producing locally heavy rain. Can not
entirely rule out a few stronger storms, mainly in the far east
where there remains a little better shear in advance of the upper
wave. Wet microburst type conditions are possible if any of the
cells can get large enough before we start to lose daytime heating.
Otherwise will just need to monitor for any training activity that
could produce localized flooding. Shower and thunderstorm activity
will decrease towards midnight as low pressure tracks northeast into
Quebec.

The cold front will settle south across the area tonight as low
pressure tracks off to the northeast. Generally expecting mostly
cloudy skies but could see some fog develop in any areas that see
breaks. Between the northerly flow off the lake and lingering cloud
cover on Sunday, lowered highs another degree or two. Temperatures
will range from the mid 70s along the southern CWA border to near 60
along the lakeshore. Some models trying to hint at shower activity
sneaking back into the west late tomorrow afternoon but would expect
this to be focused more along the front across southern Ohio so will
only carry slight chance pops in the far south. Scattered
showers and thunderstorms could return on Sunday night as
shortwave energy rides out of the Plains. Confidence in
placement is low so backed off a little on pops on Sunday night.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
The frontal boundary will still be in the vicinity, likely sitting
across southern OH on Monday and Tuesday with a couple of waves of
low pressure to move along it. The wave Tuesday will be able to
buckle the front northward into northern OH. Therefore have reduced
precip chances across the north for Monday, but still leave broad
chance PoPs for both days. Will reserve the likely or better wording
when we can time the more widespread showers/rain across. Severe
threat will be conditional on a number of factors. High pressure
will be waiting to the north to settle across the area for
Wednesday. High temperatures will remain in the 70s inland through
mid week.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
Large upper level ridge will dominate a large portion of the
nation`s mid section Wednesday night into Thursday.  The upper level
ridge is expected to shift east and be over the western slopes of
the Appalachian Mountains by Friday afternoon and then to the east
coast by Saturday.  As this transition occurs, a diving upper level
trough will swing southeast and remain positively tilted as it
approaches the Great Lakes.  Little in the way of surface low
pressure development is expected with this upper level feature
through Saturday.  Surface high pressure will persist across the
forecast area through much of this forecast period and then
gradually shift east of the area by Saturday.  The combination of
the high pressure moving east and a weak wave of low pressure that
will move east toward the area from the central Rocky Mountains will
bring a return southerly flow to the area by the end of the week.
850 MB flow will develop out of the southwest but will originate
over the Georgia coast and pump humid air into the forecast area by
Saturday.  The advancing low pressure system and increasing
dewpoints will bring a threat for showers to the area starting
Friday night.  There will be an isolated chance for thunder Friday
night as instability begins to increase slightly.  The better chance
with day time heating will be Saturday for the thunder threat.
Temperatures will gradually warm from overnight lows in the 50s
Wednesday night to the middle 60s by Saturday morning. Guidance is
trending toward more summer like highs with each period Thursday
through Saturday but will hold off on going with highs in the middle
and upper 80s by Saturday due to thunderstorm threat holding
temperatures back.

&&

.AVIATION /00Z Sunday THROUGH Thursday/...
Scattered to numerous showers and thunderstorms will continue
to move across the region through the evening. Expect to see
IFR conditions with the heavy rainfall that is being produced in
the thunderstorms. We will then await the arrival of the cold
front that is moving into NW OH as of 23Z. Very humid ahead of
this low moving boundary so expect to see some IFR ceilings
develop ahead of it. These conditions improve from north to
south on Sunday as drier air slowly filters southward across the
region.

Light southerly winds ahead of the cold front will become
westerly at most locations by 04Z. Winds become north by 12Z at
all locations.

OUTLOOK...Non VFR possible Monday through Tuesday in showers and
thunderstorms.

&&

.MARINE...
Winds will shift around to the northwest on the lake tonight as the
surface low moves across lower Ontario and the cold front across
Lake Erie. Sunday through Wednesday high pressure will remain
centered just north of the lake with the system path and a quasi-
stationary front across OH/PA. Overall winds will be light on the
lake and keep a northerly component. As one wave of low pressure
moves along the front Monday, winds will increase to 10 to 15 knots
from the northeast. Thursday high pressure across the eastern lakes
will be headed for the mid-Atlantic. No small craft advisories are
anticipated through Thursday.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
MARINE...None.

&&

$$
SYNOPSIS...KEC
NEAR TERM...KEC/Mullen
SHORT TERM...Oudeman
LONG TERM...Lombardy
AVIATION...Mullen
MARINE...Oudeman


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